Diffusion-pump



1. E; SHRADER, lmfrusion PUMP.

APPLICATION FILED JAN- 5. l9l8.

' Patented Feb. 10, 1920.

m mm N5 m s WITNESSES ATTORNEY UNITED STATES PATENT OFFICE.

JAMES E. SHRADER, 0F EDGEWOOD PARK, PENNSYLVANIA, ASSIGNOR TO WEST- INGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

DIFFUSION-PUMP.

Specification of Letters Patent.

Patented Feb. 10, 1920.

Application filed January 5, 1918. Serial No. 210,552.

To all whom it mayv concern:

Be it known that I, JAMES E. SHRADER, a citizen of the United States, and a resident of Edgewood Park, inthe county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Diffusion-Pumps, of which the following is a specification. Y

My invention relates to diffusion pumps, and it has for its object to provide apparatus of the character designated that shall be simple, compact and inexpensive in construction and highly effective in operation, said effectiveness arising, in part, from a more complete separation of the hot and cold elements of the apparatus than has hitherto been proposed.

The single figure of the accompanying drawing i fi side view, in section, of apparatus embodying my invention.

Diffusion pumps are well known wherein a blast of hot vapor is projected from a nozzle and serves to draw gas from a vessel to be exhausted, partially by an injector action and partially by the diffusion of the gas to be pumped, into the vapor blast. Said blast is then condensed and the material thereof caused to repeat the cycle, the gas thus exhausted being removed from the condensing chamber by a roughing pump.

As usually constructed in the past, the condensate formed by the cooling of the hotvapor blast has been permitted to fall upon the hot nozzle. A portion of said condensate was immediately vaporized by contact with the hot nozzle and projected into the inlet tube, counter to the incomin flow of gas, thus seriously interfering witli the ,action of the device.

In accordance with my invention, I provide. means whereby the condensate may be effectively gathered and passed through its cycle without coming into heating proximity to the hot nozzle.

Referring to the drawing for a more detailed understanding of my invention, I show the condensing chamber of a diffusion pump at 1, said condensing chamber preferably being cylindrical in form and having its longitudinal axis substantially vertical. A nozzle 2 projects through the bottom of the chamber 1 and a vapor blast may be projected therefrom into the chamber 1, as from a boiler 33. The boiler preferably contains mercury, although other fluids may be employed.

The container to be exhausted is connected to a suitable inlet tube 1 which opens into an annular space 5 surrounding thenozzle 2, and the gas, after passing through the pump, is delivered, through a tube 6, to a roughing pump of any desired form. An annular casing 7 surrounds the upper portion of the chamber 1 and serves to maintain a water jacket around said upper portion, the cooling fluid preferably entering at 8 and leaving at 9. An inwardly and upwardly turned flange 10 is provided at the lower portion of the chamber 1 and forms a trou h 11 which is drained to the boiler 3 by a tu e 12. A similar trough 13 is provided at the bottom of the annular space 5 and is drained by a tube 14.

In the operation of the device thus described, hot vapor formed within the boiler 3 issues from the upper end of the nozzle 2 and draws the gas to be exhausted from the annular space 5, partially by injector action and partially by diffusion. The vapor is condensed against the cooled walls of the chamber 1 and falls back into the trough 11, whereas the gas to be exhausted passes on to the tube 6, the desired difference of pressure between the inlet and the exhaust being maintained by the force of the blast issuing from the nozzle 2. The condensate is collected in the trough 11 and returns to the boiler 3 through the tube 12 but if, by chance, any condensate passes between the nozzle 2 and the flange 10; said material is collected in the trough 13 and returned through the tube 14.

In the devices of the prior art, all the condensate has been collected in the trough 13 and, in passing down through the space 5, portions thereof were vaporized by contact with the hot nozzle 2, at or near the end of the inlet tube 4, the resultant vapor being injected into said tube and interfering with the free passage of gas therethrough.

By my construction, it will be noted that this action is substantially entirely prevented by collecting the condensate above the tube 4 and at a point removed from the hot nozzle 2. I

While I have shown my invention in its preferred form, it will be obvious to those skilled in the art that it is susceptible of Va to be operated upon, said inlet tube terminating slightly below the upper end of said nozzle, and means for preventing the impact of condensate, forming within said chamber, upon said nozzle adjacent the end of said inlet tube.

2. In a diffusion pump, the combination with means providing a condensing chamber, of a nozzle projecting thereinto at the bottom thereof, means for projecting a hotvapor blast through said nozzle, inlet and outlet tubes for the entry and exit of the gas to be operated upon, said inlet tube terminating slightly below the upper end of said nozzle, and means for collecting the condensate falling on the walls of said chamber and for diverting said condensate from impact upon said hot nozzle.

3. In a difi'usion pump, the combination with means providing a condensing chamber, of a nozzle projecting therein at the bottom thereof, means for projecting a hotvapor blast through said nozzle, inlet and outlet tubes for the entry and exit of the gas to be operated upon, said inlet tube terminating in an annular space surrounding said nozzle, an annular trough surrounding and spaced from said nozzle and arranged to collect all condensate forming upon the walls of said chamber and to prevent said condensate from entering said antween the inlet passage and the point ofdischarge of the blast for trapping and conducting away the vapor condensed in the condensing chamber.

'5. A difi'usion pump comprising means providing a condensing chamber having spaced inlet and outlet passages for the gas to be operated upon, a nozzle disposed within the condensing chamber at a point between the passages, means for supplying a hot-vapor to the nozzle, means for trapping vapor condensed in the condensing chamber at a point between the discharge end of the nozzle and the inlet passage of the chainber and means for returning the condensed vapor to the source ofvapor supply.

In testimony whereof, I have hereunto subscribed my name this 20th day of Dec., 1917.

JAMES E. SHRADER. 

